This invention relates generally to methods and apparatus for radiation imaging systems and, more particularly, to methods and apparatus for combating cone beam and helical artifacts utilizing weighted generalized helical interpolation.
In multislice computed tomographic (CT) imaging systems, a detector array is segmented so that a plurality of parallel or quasi-parallel slices of projection data are acquired and processed to construct a plurality of images corresponding to several slices though a volume. A range of pitches exists for which measurements are available at least at two source locations. Samples acquired at different source positions are known as xe2x80x9cconjugate samples.xe2x80x9d
In some known imaging systems, using High Speed (HS) mode in which pitch values are relatively high, projection data sets do not include conjugate samples. Therefore, the cone beam and helical interpolation induced artifacts may not be effectively compensated resulting in projection images which may include image artifacts caused by helical interpolation and cone beam artifacts.
In one aspect, a method for reducing imaging artifacts in at least one image representative of an object with a scanning imaging system is provided. The imaging system has a multislice detector array and a radiation source configured to emit a radiation beam through the object and towards the multislice detector array. The multislice detector array has a plurality of detector elements arranged in a plurality of detector rows. The method includes scanning the object with the scanning imaging system to acquire a plurality of projection data acquired from a plurality of detector rows including two end rows and a plurality of interior detector rows. The method also includes defining a first plane of reconstruction (POR) for a particular detector row, and defining a second plane of reconstruction (POR) for the particular detector row.
In another aspect, a method for reducing imaging artifacts in at least one image representative of an object with a scanning imaging system is provided. The imaging system has a multislice detector array and a radiation source configured to emit a radiation beam through the object and towards the multislice detector array. The multislice detector array has a plurality of detector elements arranged in a plurality of detector rows. The method includes scanning the object with the scanning imaging system to acquire a plurality of projection data acquired from a plurality of detector rows including two end rows and a plurality of interior detector rows. The method also includes defining a first plane of reconstruction (POR) for each detector row, and defining a second plane of reconstruction (POR) for each interior detector row. The method also includes deriving a weighting function using the first POR and the second POR.
In another aspect, a medical imaging system for estimating a material composition of an imaged object is provided. The system includes a detector array including a plurality of detector rows including two end detector rows and a plurality of interior detector rows. The system also includes at least one radiation source, and a computer coupled to the detector array and radiation source. The computer is configured to scan the object with the scanning imaging system to acquire a plurality of projection data acquired from a plurality of detector rows including two end rows and a plurality of interior detector rows. The computer is also configured to define a first plane of reconstruction (POR) for a particular detector row, and define a second plane of reconstruction (POR) for the particular detector row.
In yet another aspect, a medical imaging system for estimating a material composition of an imaged object is provided. The system includes a detector array including a plurality of detector rows including two end detector rows and a plurality of interior detector rows. The system also includes at least one radiation source, and a computer coupled to the detector array and radiation source. The computer is configured to scan the object with the scanning imaging system to acquire a plurality of projection data acquired from a plurality of detector rows including two end rows and a plurality of interior detector rows. The computer is also configured to define a first plane of reconstruction (POR) for each detector row, and define a second plane of reconstruction (POR) for each interior detector row. The computer is also configured to derive a weighting function using the first POR and the second POR.
In one aspect, a computer readable medium encoded with a program executable by a computer for reconstructing a three-dimensional dataset representative of an imaged object is provided. The program is configured to instruct the computer to scan the object with a scanning imaging system to acquire a plurality of projection data acquired from a plurality of detector rows including two end rows and a plurality of interior detector rows. The program is also configured to define a first plane of reconstruction (POR) for a particular detector row, and define a second plane of reconstruction (POR) for the particular detector row.
In another aspect, a computer readable medium encoded with a program executable by a computer for reconstructing a three-dimensional dataset representative of an imaged object is provided. The program is configured to instruct the computer to scan the object with the scanning imaging system to acquire a plurality of projection data acquired from a plurality of detector rows including two end rows and a plurality of interior detector rows. The program is also configured to define a first plane of reconstruction (POR) for each detector row, and define a second plane of reconstruction (POR) for each interior detector row. The program is also configured to derive a weighting function using the first POR and the second POR.